What's the difference between i.e. and e.g.?
c.1600 (adj.), 1620s (n.), from Latin climactericus, from Greek klimakterikos "of a critical period," from klimakter "rung of a ladder" (see climax (n.)). A critical stage in human life, a period supposed to be especially liable to change. By some, held to be the years that are multiples of 7 (7, 14, 21, etc.), by others only the odd multiples (7, 21, 35, etc.), and by still others the multiples of 9. The Great Climacteric was the 63rd year (7x9), supposed to be especially critical.
climacteric cli·mac·ter·ic (klī-māk'tər-ĭk, klī'māk-těr'ĭk)
A period of life characterized by physiological and psychic change that marks the end of the reproductive capacity of women and terminates with the completion of menopause.
A corresponding period sometimes occurring in men that may be marked by a reduction in sexual activity, although fertility is retained.